The processing of diced wafers, for example, magnetic disk file sliders, by transporting the dice mounted on a wafer dicing tape, provides many benefits in view of the reduced sizes of the sliders having improved technology. Wafer dicing tape, typically referred to as "tape", is a tape with high toughness, such as wide polyvinyl chloride membrane, with adhesive applied to one side, mounted in a frame. Rows of sliders mounted on the tape are held securely in position with great accuracy for cleaning, inspecting, processing, parting, and sorting. Slider and row verification is reduced to a minimum in that, once a die is mounted on the tape, it is not likely to be inadvertently moved around or repositioned during processing.
In order to be workable and avoid inadvertent repositioning of the sliders, the adhesive must be strong. However, when removing a slider from the tape with a removal tool such as a vacuum picker, the force from the vacuum picker is not adequate to overcome the adhesive holding force of the tape.
One prior art approach used to remove a slider attached to a tape includes positioning a needle directly under the slider. More specifically, the needle is instantaneously pushed up into the tape, potentially puncturing the tape, to lift the slider from the tape. Expensive controls are required to limit tape puncture. The needle can transfer a small amount of tape adhesive to the attachment side of the slider if it punctures the tape. The transferred adhesive in itself is a contaminant on the slider. Because of the nature of adhesives, the transferred adhesive can also attach other contaminants to the slider. In addition, the adhesive can also free itself from the slider and contaminate other parts in subsequent operations and processes as well as the finished product.
Another prior art approach includes heating the tape to reduce the strength of the adhesive to allow removal of the sliders by a picker. This approach has proven to be inconsistent in providing clean sliders, because heating the adhesive does not assure that the adhesion between the slider and the adhesive is the first to weaken.
A third prior art approach described in U.S. Pat. No. 4,590,667 of Simon, describes a knife edge for presenting a row of semiconductor devices such as LED's, mounted on a non-elastic membrane with an ultra-violet sensitive adhesive, to a vacuum fixture. An ultra-violet light is flashed to facilitate lifting the devices from the membrane as they pass over the knife edge. The vacuum fixture may be provided with a lip to engage the row of devices to "slide" the entire row off the membrane as the membrane is moved across the knife edge.
The use of an ultra-violet sensitive adhesive and flashing an ultra-violet light for separating sliders from a tape, like heating the adhesive, above, would not assure that the adhesion between the slider and the adhesive is the first to deteriorate. Instead, the adhesion between the adhesive and tape may be the first to deteriorate. It is likely that some of the adhesive will remain attached to, and contaminate, the slider.
Furthermore by engaging the sliders with a lip while the tape is moving requires the entire row of devices to be removed at once. Selective device removal from the membrane is not possible using this method.